Converter for Providing Several Output Voltages

Abstract

A device for providing several output voltages in a DC/DC converter, which comprises: a series inductance ( 14 ) provided with alternating magnetic energy via a loading circuit ( 11 ); a first output circuit comprising a first diode ( 16 ) coupled to the inductance, and a first capacitor ( 17 ) for providing a first output voltage to a first output load ( 18 ); a control circuit ( 19 ) for controlling the loading circuit to provide sufficient power to the inductance in order to control the first output voltage; at least one auxiliary output circuit comprising an auxiliary diode ( 21 ), a switching element ( 22 ) and an auxiliary capacitor ( 23 ) for providing an auxiliary output voltage to an auxiliary output load ( 24 ), the auxiliary output voltage being lower than the first output voltage; and at least one auxiliary control circuit ( 25 ). The switching element is controlled to be “on” before the voltage at an anode of the auxiliary diode is higher than the auxiliary voltage of the auxiliary capacitor, and to be “off” when a sufficient energy has been transferred to the auxiliary output circuit to maintain the auxiliary output voltage at a predetermined auxiliary output voltage.

1 . A converter for providing several output voltages, the converter comprising:
 a series inductance ( 14 ) provided with alternating magnetic energy via a loading circuit ( 11 );   a first output circuit comprising a diode ( 16 ) coupled to said inductance, and a capacitor ( 17 ) for providing a first output voltage to a first output load ( 18 );   a control circuit ( 19 ) for controlling the loading circuit to provide sufficient power to said inductance in order to control said first output voltage;   at least one auxiliary output circuit comprising an auxiliary diode ( 21 ), a switching element ( 22 ), and an auxiliary capacitor ( 23 ) for providing an auxiliary output voltage to an auxiliary output load ( 24 ), said auxiliary output voltage being lower than said first output voltage; and   at least one auxiliary control circuit ( 25 ) for controlling said switching element to be “on” before the voltage at an anode of the auxiliary diode is higher than the auxiliary voltage of the auxiliary capacitor, and to be “off” when a predetermined time has elapsed that is related to the output voltage of said auxiliary circuit.   
   
   
       2 . The converter of  claim 1 , wherein said switching element is switched “on” when the voltage of said inductance is negative and the auxiliary diode is reverse biased. 
   
   
       3 . The converter of  claim 1 , wherein said switching element is switched “on” after the time (t 0 ) when the inductance voltage is zero but before the time (t 1 ) when the inductance voltage has reached the auxiliary output voltage. 
   
   
       4 . The converter of  claim 1 , wherein said auxiliary control circuit comprises a timing capacitor ( 45 ), which is connected to a negative voltage during a negative half period of the inductor voltage and is charged during the positive half period of the inductor voltage in order to increase the voltage until a predetermined voltage has been obtained, thereby effectively switching “off” said switching element. 
   
   
       5 . The converter of  claim 4 , wherein said timing capacitor is connected to a current source ( 49 - 51 ) inversely controlled by said auxiliary output voltage. 
   
   
       6 . The converter of  claim 1 , further comprising at least one further auxiliary circuit connected to said inductor in parallel with the first auxiliary circuit. 
   
   
       7 . The converter of  claim 1 , wherein said inductor has a winding with a center tap, and said main output voltage is generated from one part of the inductor winding during one half of a cycle of the inductor voltage and from the other part during the other half of the cycle, to provide a main output voltage with double ripple frequency. 
   
   
       8 . The converter of  claim 1 , wherein said inductor has a winding with a center tap, and said auxiliary voltage is generated from one part of the inductor winding during one half of a cycle of the inductor voltage and from the other part during the other half of the cycle, to provide an auxiliary output voltage with double ripple frequency. 
   
   
       9 . The converter of  claim 6 , wherein some components of the auxiliary circuits are common to the auxiliary circuits. 
   
   
       10 . The converter of  claim 1 , wherein said inductor has a winding with a center tap, and at least one auxiliary voltage is generated from one part of the inductor winding during one half of a cycle of the inductor voltage and at least another auxiliary voltage is generated from the other part during the other half of the cycle. 
   
   
       11 . The converter of  claim 1 , wherein said inductor has a further winding or a tap having a number of turns different from the winding connected to the main circuit and being connected to at least one auxiliary circuit.